Amino(halo)silanes are attracting attention owing to their chemical properties and potential usage as film deposition precursors across a wide range of industries. The deposited films may be useful as semiconductor dielectric materials and coatings, photovoltaic device coatings, refractory optical coatings and aerospace materials.
Synthesis of amino(halo)silanes has been achieved via aminolysis of halosilanes (J. Chem. Soc. 1952, pp. 2347-2349). The synthesis also produces ammonium halide salt byproducts.
US2012/0277457 to Lehmann et al. discloses methods of making aminosilanes as well as intermediate compounds such as haloaminosilane compounds. The haloaminosilane compounds are made by reacting a halosilane having the formula HnSiX4-n, wherein n is 0, 1, or 2 and X is Cl, Br, or a mixture of Cl and Br, and an amine to provide the haloaminosilane compound.
US2013/0078392 to Xiao et al. discloses halogenated amino(halo)silane precursors having the formula XmR1nHpSi(NR2R3)4-m-n-p where X is Cl, Br and I. The precursors are synthesized by reacting dichlorosilane or trichlorosilane with a secondary amine (i.e., HNR2 or 2,2-dimethylpiperidine) or Li amine (Li—NR2 or Li-2,2-dimethylpiperidine) in an organic solvent or solvent mixture and using a tertiary amine (i.e., NR3) to absorb the hydrogen chloride byproduct.
Xiao et al. disclose another family of Si-containing precursors in US2013/0323435 which have the formula (R1R2N)n—SiH3-nSiH3 wherein R1 is selected from linear or branched C3 to C10 alkyl group, linear or branched C3 to C10 alkenyl group, linear or branched C3 to C10 alkynyl group, C1 to C6 dialkylamino group, electron withdrawing group, and C6 to C10 aryl group; R2 is selected from hydrogen, linear or branched C1 to C10 alkyl group, linear or branched C3 to C6 alkenyl group, linear or branched C3 to C6 alkynyl group, C1 to C6 dialkylamino group, C6 to C10 aryl group, linear or branched C1 to C6 fluorinated alkyl group, electron withdrawing group, and C4 to C10 aryl group; optionally wherein R1 and R2 are linked together to form ring selected from substituted or unsubstituted aromatic ring or substituted or unsubstituted aliphatic ring; and n=1 or 2. The Si-containing precursors are synthesized by reacting a monohalodisilane or lower molecular dialkylaminodisilane with an amine in an organic solvent or solvent mixture.
Additionally, Xiao et al also disclose another family of Si-containing precursors in US2013/0319290 which have the formula (R1R2N)—SiH2SiH2—(NR3R4) and methods for forming silicon-containing films and wherein R1 and R3 are independently selected from linear or branched C3 to C10 alkyl group, a linear or branched C3 to C10 alkenyl group, a linear or branched C3 to C10 alkynyl group, a C1 to C6 dialkylamino group, an electron withdrawing and a C6 to C10 aryl group; R2 and R4 are independently selected from hydrogen, a linear or branched C3 to C10 alkyl group, a linear or branched C3 to C10 alkenyl group, a linear or branched C3 to C10 alkynyl group, a C1 to C6 dialkylamino group, an electron withdrawing, and a C6 to C10 aryl group; and wherein any one, all, or none of R1 and R2, R3 and R4, R1 and R3, or R2 and R4 are linked to form a ring. The Si-containing precursors are synthesized by reacting a dichlorodisilane with an amine in an organic solvent or solvent mixture.
Harald Stüger et al. disclose synthesis of multifunctionalized disilane derivatives from bis(trimethylsilyl)aminopentachlorodisilane, 1,2-bis[bis(trimethylsilyl)amino]tetrachlorodisilane, or bis(phenyldimethylsilyl)aminopentachlorodisilane by reacting Si2Cl6 with LiN(SiMe3)2 or LiN(SiMe2Ph)2. (J. Organometallic Chem., 547 (1997), pp. 227-233).
Another published synthetic route utilizes protonation of aminosilanes using a haloacid (‘Preparations, Properties, and Vibrational Spectra of some (dimethylamino)halogenosilanes,’ Anderson et al., J. Chem Soc. Dalt. Trans., 1987, 3029-3034). The synthesis also produces ammonium halide salt byproducts.
Disilane containing precursors bearing both alkyl and amino groups have been disclosed for deposition of SiCN thin films by Tsukada and Dussarrat in JP 2006096675. A phenyl-substituted disilane is reacted with HCl, wherein the Cl replaces the phenyl to produce a chlorodisilane. The resulting chlorodisilane is reacted with an alkali amine (i.e., LiNMe2) to produce the amino-substituted disilane product.
Passarelli et al. (‘Aminolysis of the Si—Cl bond and ligand exchange reaction between silicon amido derivatives and SiCl4: synthetic applications and kinetic investigations,’Dalt. Trans., 2003, 413-419) have shown the utility of synthesis of amino(chloro)silanes using a ligand exchange route wherein an aminosilane SiCln(NR2)4-n is reacted with a chlorosilane SiCl4 in the appropriate ratio to produce the targeted products without the formation of ammonium halide salt byproducts.
A need remains for synthesis methods to produce bromo- and iodo-aminosilicon precursors that may be suitable for use in film deposition processes.